Apparatus for making concrete



Jan. 7, 1930. v K. PIEHLER 1,743,002

APPARATUS FOR MAKING CONCRETE Filed Feb. 2, 1927 Fig. 1

Patented Jan. 7, 1930 V UNITED. STATES KARL PIEI-ILER, OF LEIPZIG-GQHLIS, GERMANY APPARATUS FOR MAKING CONCRETE Application filed February 2, 1927, Serial No. 165,382, and in Germany March 11, 1926.

This invention relates to apparatus for mixing concrete and it has for its object the provision of an annular drum forming in cooperation with blades suitably constructed and arranged a mixing and discharging zone defining a central region to which a trans-- portation receptacle may be introduced through an end of said drum for the purpose of charging the ingredients of concrete into said drum during the operation of said drum, and in which region the transportation receptacle may be let remain during the mixing and discharging period of the mixer, without interfering with the mixing operation, and automatically receiving the mixed concrete when the direction of rotation of the drum is reversed.

Mixing drums have become known into which the mixing vessels are brought into and rotate with the rotating drum and form, during the mixing operation, part of said mixin drum.

Mixers have further become known in which a vessel containing material to be mixed is inserted into the drum and tipped in the same. In these mixers the drum must be stopped during the insert-ion of the vessel which is then tipped and removed from the drum, as otherwise the unmixed material would be thrown at once into the charging vessel by the permanently rotating lifting plates of the mixing drum. The material will further settle in mixers of this type in irregularly mixed combinations onto the track in the drum as this drum can rotate only in one direction. so that for every operation the vessel has to be several times inserted and removed.

Concrete mixers are further known the drum of which is adapted to rotate in diiterent directions, the material being mixed when the drum rotates in one direction and discharged when the drum is rotating in the other direction. In mixers of this kind the material is supplied to the drum from the outer side by means of slides or charging boxes, the emptying of the drum being eifected by rejecting "plates in the drum, designed to supply the mixed material into transport- 0 ing vessels standing outside the drum.

According to the invention the material to be mixed is brought into the drum by means of commonly used hand carts or trough tipping wagons. The cart or wagon is tipped in the drum, emptied and put upright again, and remains in the drum during the mixing. Only. after the direction of rotation of the drum has been reversed the finished mixed material is charged again into this cart or wagon by means of shovels arranged in the mixing drum. It is consequently not necessary, to insert the cart or wagon into and to remove the same repeatedly from the drum.

A mixing drum designed for carrying out the improved mixing process is shown, by way of example, in the accompanying drawings in which Fig. 1 is a side elevation of the mixing machine. i

Fig. 2 is a plan view of Fig. 1.

In the drawing a designates an annular mixing drum of a substantially troughshaped cross section running on rollers b and adapted to be rotated in opposite directions E and M (emptying and mixing rotations) by means of an operating shaft in any known or suitable way. The drum or is open at its ends so as to permit the endwise free entrance or exit of suitable transportation meansfor example of an ordinary dumping car 9, so (3011- structed that it may assume, when being within the drum 0;, its upright or dumped positions, as indicated in the drawing with full and dotted lines, and without interfering with; the rotating drum. For guiding the car 9 into and out of the drum I preferably arrange adjacent the bottom portion thereof a stationary bridge h arranged at a suitable distance above the inner periphery of the drum, as shown, so that the drum may freely rotate without interfering with the dumping car 9 or with its passing into and outof the interior of the drum. f designates an eye fixed to the hopper (Z of the dumping car 9 and adapted to receive a removable rod, not shown, for dumping the car.

The drum a is provided between its tapering walls with inclined scoop-shaped blades 6 the side of each blade which makes an obtuse angle with the drum wall being for mixing,

i and the side which makes an acute angle with illustrated in Fig. 2 more in detail. When the 'material to be mixed has been dischar ed into the drum and the same is rotated in t e mixing direction, as indicated by the arrow M in Fig. 1, that is, for the embodiment shown, in a clockwise direction, the blades are acting with their obtuse sides to the materials, simply mixing them by lifting them, part way up, whereupon the materials fall ofi on account of the downward inclination of the upwardly going blade 6. When the concrete has been sufficiently mixed the rotation of the drum a is reversed, the same now rotating in the emptying or counter-clockwise direction as indicated by the arrow E in-Fig. 1. The blades 6 are now acting as real shovels, picking up and lifting the mixed material and carrying it substantially to the top of the drum before dropping it, whereupon it is delivered by gravity into the waiting car 9. I

This operation thus permits one to leave the dumping car 9 or other transporting means having an open-top within the drum during mixing and to refill it with, the mixed material after the mixing period, by a simple reversal of the direction of drum rotation. Accordingly when the dumping car is pushed into the interior of the drum through the open ends thereof and alongthe rails of the stationary bridge h its hopper d is dumped in order to discharge the concrete or other materials to be mixel into drum a. Thereupon the'hopper can be immediately returned into its upright position and thedumping car left within the drum, when the same is being rotated in the direction M for mixing the materials. 7 During thisrotation the hopper d remains empty as the blades are, for the reasons stated, un-

able to lift the materials upward and return them into the hopper. When, after the mixing operation being completed, the drum is rotated in the direction E however, the mixed concrete is picked upby the shovels e constituted by the cooperating blades and drum walls and dropped off from above the hopper d, so that the same is recharged and can be removed. With a machine according to the invention it is thus possible to introduce the car into the moving drum, to leave the transportation means within the drum during the whole mixing operation and to immediately recharge it thereafter by a simple reversal of the drum rotation.

I claim V A concrete mixing machine comprising an annular mixing drum adapted to have a transportation receptacle positioned within it during the mixing period and being filled while within it during the filling period,

means for rotating mixing drum in opposite 

